Answer
variation constant $=k=320$
equation of variation: $y=\frac{320}{x}$
Work Step by Step
$y$ varies inversely as $x$ so the variation is inverse.
The equation of an inverse variation is of the form $y=\frac{k}{x}$ where $k$ is the constant of variation.
To find the value of $k$ substitute the given values of $x$ and $y$ into $y=\frac{k}{x}$ to obtain:
$$y=\frac{k}{x}
\\40=\frac{k}{8}
\\8(40) = k
\\320=k$$
Thus, the equation of the variation is $y=\frac{320}{x}$.
